呂琴
Traditional plant breeding involves crossing varieties of the same species in ways they could cross naturally.For example,disease-resistant varieties of wheat have been crossed with high-yield wheat to combine these properties.This type of natural gene exchange is safe and fairly predictable.
Genetic engineering(GE)involves exchanging genes between unrelated species that cannot naturally exchange genes with each other.GE can involve the exchange of genes between vastly different species――e.g.putting scorpion toxin genes into maize or fish antifreeze genes into tomatoes.It is possible that a scorpion toxin gene,even when it is in maize DNA,will still get the organism to produce scorpion toxin――but what other effects may it have in this alien environment?We are already seeing this problem――adding human growth hormone genes to pigs certainly makes them grow――but it also gives them arthritis and makes them cross-eyed,which was entirely unpredictable.
It will be obvious,for example,that the gene for human intelligence will not have the same effect if inserted into cabbage DNA as it had in human DNA――but what side-effect would it have?In other words,is GM food safe to eat?The answer is that nobody knows because long-term tests have not been carried out.
Companies wanting a GM product approved in the UK or USA are required to provide regulatory bodies with results of their own safety tests.Monsantos soya beans were apparently fed to fish for 10 weeks before being approved.There was no requirement for independent testing,for long-term testing,for testing on humans or testing for specific dangers to children or allergic people.
The current position of the UK Government is that “There is no evidence of long-term dangers from GM foods.” In the US,the American Food and Drug Administration is currently being prosecuted for covering up research that suggested possible risks from GM foods.
食用轉基因食品安全嗎
傳統的植物育種包括同一種類變種的雜交,它們的雜交方式是自然的。例如,小麥的抗病變種與高產量的小麥雜交,結合形成一些特性。這一類型的自然基因交換很安全,并且其結果也是可以預見的。
轉基因工程包括不相關物種之間的基因交換,它們之間的交換方式并不自然。轉基因工程指截然不同的物種交換基因,如將蝎毒素基因植入玉米中或將魚的抗凍基因植入西紅柿中。即使在玉米基因中,蝎毒素基因也有可能獲得生產蝎毒素的有機體,但是在這個陌生的環境下,它還會產生什么影響呢?我們已經遇見了這個問題:將人類生長激素注入豬的體內,它能促進豬的成長,但同時這一激素也讓豬患上了關節炎和斜視疾病,這種情況是完全是沒有預料到的。
打個比方,將本應在人體基因內的人類智力基因植入白菜的基因內,顯而易見,效果是不一樣的,但是這么做有什么副作用呢?換言之,食用轉基因食品安全嗎?沒有人知道這個答案,因為人們還沒有進行長期的測試。
在英國或者美國,公司若想一種轉基因食品獲得批準,那么它們必須出具監管機構對其產品自身安全檢測做出的結果證明。孟山都公司的大豆在獲得批準前,已經用其喂魚十個星期了。沒有要求規定需要進行獨立測試、長期測試和人體測試,或針對兒童或過敏群眾的特定危險進行的測試。